Backflow Preventer Calculator

Determine the correct backflow prevention device type, size, pressure loss, and estimated installation cost based on hazard level.

Flow Rate

GPM

Size device to match pipe capacity: 3/4" = 10 GPM; 1" = 20 GPM; 2" = 100 GPM typical

Downstream Pressure Loss

psi

Hazard Level

Low hazard: AVB or DCVA; High hazard: RPBA required per IPC 608 and local water authority

Supply Pipe Size

inches

Tab to move between fields

Recommended Device

3 (1=AVB, 2=PVB, 3=DCVA, 4=RPBA)

Minimum Device Size

2 inches

Total Pressure Loss11 psi

Estimated Install Cost$1,049.00

How to Use This Calculator

Enter the system flow rate in GPM to size the backflow preventer.
Set the hazard level: 1 = low (irrigation), 2 = medium (chemical boilers), 3 = high (toxic connections).
Enter your supply pipe size to match the device connection diameter.
Review the Recommended Device type — high-hazard applications require a Reduced Pressure Zone (RPZ) assembly.
Use the Estimated Install Cost to budget for device purchase and licensed installation.

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